2023, 52(4): 20220862. doi: 10.3788/IRLA20220862
[Abstract](47) [FullText HTML] (5) [PDF 1886KB](19) [Cited by] ()
Research on laser self-mixing nano-displacement measurement based on plane reflective holographic grating
2023, 52(4): 20220676. doi: 10.3788/IRLA20220676
[Abstract](35) [FullText HTML] (4) [PDF 1947KB](14) [Cited by] ()
2023, 52(4): 20220646. doi: 10.3788/IRLA20220646
[Abstract](26) [FullText HTML] (1) [PDF 2082KB](10) [Cited by] ()
Three-dimensional measurement of geometrical parameters of cutting tools based on depth from focus method
2023, 52(4): 20220686. doi: 10.3788/IRLA20220686
[Abstract](43) [FullText HTML] (2) [PDF 2691KB](13) [Cited by] ()
Correction of atmospheric refraction error based on correlation analysis of star measurement residual data
2023, 52(4): 20220732. doi: 10.3788/IRLA20220732
[Abstract](37) [FullText HTML] (5) [PDF 1539KB](11) [Cited by] ()
2023, 52(3): 20220618. doi: 10.3788/IRLA20220618
[Abstract](43) [FullText HTML] (4) [PDF 7981KB](22) [Cited by] ()
Long and narrow trajectory measurement system based on centroid matching optimization in close-up scenes
2023, 52(3): 20220574. doi: 10.3788/IRLA20220574
[Abstract](50) [FullText HTML] (6) [PDF 2749KB](9) [Cited by] ()
2023, 52(3): 20220554. doi: 10.3788/IRLA20220554
[Abstract](66) [FullText HTML] (13) [PDF 2829KB](26) [Cited by] ()
2023, 52(2): 20220338. doi: 10.3788/IRLA20220338
[Abstract](73) [FullText HTML] (19) [PDF 9962KB](33) [Cited by] ()
In order to improve the quality of automatic fiber placement and assist on-site personnel to quickly detect defects, this paper proposes a real-time instance segmentation network named Trans-Yolact, which is based on Transformer. The Trans-Yolact is used to detect, classify and segment multi-spectrum images of composite material defects. Based on Yolact, aiming at the characteristics of composite material defects, Trans-Yolact's detection ability of composite material defects is enhanced from the two dimensions of space domain and channel domain. In the spatial domain, the convolution kernels have the limitation of spatial scale. The detection of narrow, long, large-size defects is not effective. Therefore, this paper adopts the BoTNet of the CNN+Transformer architecture as backbone; at the same time, the Transformer is introduced into the FPN structure of the Yolact network to enhance the network's ability to obtain information from non-local spaces. In the channel domain, the infrared and visible simultaneous detection method is adopted, and the shallow structure of the backbone is improved, which is divided into visible channel, infrared channel, and mixed channel. Channel domain attention mechanism is introduced in mixed channel. Enhance the comprehensive judgment ability of the network for infrared and visible images. The results show that the mAP of Trans-Yolact for composite defect detection is 88.0%, which is 5.5% higher than Yolact network, and the AP of narrow defects such as miss and twist are increased by 15.2% and 5.1%. The AP of foreign defects including some large-scale defects is increased by 9.1%. Finally, the Trans-Yolact network is pruned. After pruning, the amount of floating-point operations per second (FLOPs) and parameters are reduced by 26.5% and 44.7% compared with Yolact network. The number of detection frames is increased by 58%, reaching 57.67 fps. And the online test is carried out on the large-scale gantry composite material automatic laying equipment, which can meet the real-time detection and segmentation of composite material defects under the maximum laying speed of 1.2 m/s in the production process.
2023, 52(2): 20220593. doi: 10.3788/IRLA20220593
[Abstract](72) [FullText HTML] (14) [PDF 2099KB](45) [Cited by] ()
In order to improve the measurement accuracy, stability and efficiency of the existing 3D coordinate positioning technology, a deep-learning-based point-diffraction interferometer for 3D coordinate measurement method was proposed. A deep neural network was designed for coordinate reconstruction of the point-diffraction interference field. The phase difference matrix was used as the input to construct the training dataset, and the coordinates of point-diffraction sources were used as the output to train the neural network model. The well-trained neural network was used to process the measured phase distribution initially and the phase information was converted to the coordinates of point-diffraction sources. According to the obtained coordinates of point-diffraction sources, the initial particles of the particle swarm optimization algorithm were further modified, and then the high-precision three-dimensional coordinate was reconstructed. This neural network provides a feasible method to establish the nonlinear relationship between the phase distribution of the interference field and the coordinates of the point-diffraction sources, and significantly improves the accuracy, stability and measurement efficiency of the 3D coordinate positioning. In order to verify the feasibility of the proposed method, numerical simulation and experimental verification were carried out, and different methods were used for repeated comparison and analysis. The results show that the single measurement time of the proposed method is about 0.05 s, and the experimental accuracy can reach the submicron magnitude. The mean and RMS values of the repeatability experiments are 0.05 μm and 0.05 μm, respectively, which proves the feasibility of the proposed method and its good measurement accuracy and stability. It provides an effective and feasible method for 3D coordinate positioning.
2023, 52(2): 20220488. doi: 10.3788/IRLA20220488
[Abstract](138) [FullText HTML] (46) [PDF 5100KB](40) [Cited by] ()
The resolution and light collection ability of telescope were directly proportional to its aperture. With the increasingly strict requirements of human beings for the resolution of telescopes, the size of telescope mirrors would be also increasing. With the increasing size of the mirror, the mirror seeing became more and more important. Mirror seeing mainly referred to the degradation of image quality caused by turbulence on the mirror surface. When the mirror size exceeded the local atmospheric turbulence scale, we had to consider the influence of this factor on imaging or processing. The working environment of the system would affect the mirror seeing to a certain extent, so the mirror seeing was also of great significance to the integrated detection process. Therefore, in order to improve the surface accuracy of mirror processing and the integration effect of the detection system, it was necessary to accurately measure the mirror seeing of the instrument, so as to provide judgment for its processing detection and application integration. In our work, one-dimensional detection (autocollimator method, etc.), two-dimensional detection (slope/curvature method, holographic wavefront sensing method and shearing interference method, etc.) and three-dimensional detection (holographic particle velocimetry and temperature field method, etc.) were described from three aspects: principle, research status and application in mirror seeing. By introducing the detection methods for different scenes and detection requirements, it had a good guiding significance for the detection of mirror seeing.
Optimization and validation of coherent point drift for planar-array-based point cloud in space pose measurement
2023, 52(2): 20220367. doi: 10.3788/IRLA20220367
[Abstract](77) [FullText HTML] (15) [PDF 4964KB](29) [Cited by] ()
The planar-array-based imaging radar can achieve transient 3D detection and is suitable for pose measurement of moving platforms or non-cooperative targets. A multi-view point cloud auto-registration method for pose measurement of spatially non-cooperative targets was proposed for non-uniform grid point clouds with crosstalk characteristics between adjacent pixels. Based on the principle of improved coherent point drift (CPD), the method treats the target point cloud as the data distribution set and the source point cloud as the set of center-of-mass points of Gaussian mixture model (GMM). The likelihood function of the constructed GMM model is solved by using Bayesian posterior probability formula and Expectation-Maximum (EM), and the weight of the point set are adaptively adjusted by the overlap of the point clouds in the optimization process. The distance residuals between source point set after one EM iteration are ranked, the optimal transformed point cloud pair is selected, and the local perturbation quantity is established using the nearest neighbor method to obtain the spatial transformation matrix for each drift iteration. To avoid getting into local solutions, the attributes of the point set involved in the drift operation are alternated by supervising the mean square error update rate of the point cloud. For spatially targets, two simulation conditions are established to obtain multi-view non-cooperative target point cloud datasets. The results show that the method is robust under the strong noise and pixels blurring interference, and the average largest common point set corresponding is improved by approximately 61% compared with the other coarse-fine registration strategy, which can be applied to the non-cooperative target pose measurement under the spatial planar-array-based 3D imaging platform.
Research on high precision temperature control system using linear auto disturbance rejection technique
2023, 52(2): 20210813. doi: 10.3788/IRLA20210813
[Abstract](80) [FullText HTML] (19) [PDF 1880KB](35) [Cited by] ()
With the development of photoelectric measurement technology, infrared gas detection technology is widely used in many fields. Temperature has an important influence on the detection of gas concentration and isotopic abundance. The traditional temperature control system using proportional integral differential (PID) control algorithm has the disadvantages of overshoot, slow response time and low precision. Firstly, COMSOL software is used to determine the heating structure by finite element analysis. Secondly, the STM32 single chip microcomputer is used to collect real-time temperature data through 16 bit AD chip LTC1864. Finally, the linear auto disturbance rejection algorithm (LADRC) is used to adjust the PWM wave that achieve the high-precision and real-time dynamic adjustment of the system temperature by controlling the semiconductor cooler (TEC). Under the temperature of 19.8 ℃ condition, an temperature control experiments with a target temperature of 32 ℃ is carried out. The results show that the standard deviation of temperature fluctuation is 0.0357 ℃. Compared with the temperature control system using PID algorithm, it has the advantages of no overshoot, fast response time and high precision.
Star simulator light source spectral matching accuracy improvement method by two-dimensional partition feedback control
2023, 52(2): 20220451. doi: 10.3788/IRLA20220451
[Abstract](81) [FullText HTML] (21) [PDF 3767KB](29) [Cited by] ()
To improve the spectral matching accuracy of the star simulator light source system, firstly, a star simulator light source system based on digital micromirror is designed and built. Secondly, the spectral fitting of the genetic algorithm is performed according to the regional spectrum calibrated by wavelength, The results show that the scheme exits a certain matching error between the fitted spectrum and the target spectrum. Finally, in order to improve the accuracy of spectral matching, an error feedback and accuracy improvement method is proposed to divide the region into two-dimensional wavelength and energy. The experiment simulates light sources with color temperatures of 2550 K, 4766 K, 6576 K, and 8910 K. The results show that, compared with the feedback method of one-dimensional division in the wavelength direction, the maximum error of spectral matching decreases by 55.7%, 50.6%, 45.2%, and 42.2%, respectively, which significantly improves the spectral matching accuracy of the star simulator light source system. The study aims to compensate for the angle measurement error caused by the spectral match error, which improves the star sensor's calibration accuracy.
2023, 52(2): 20220408. doi: 10.3788/IRLA20220408
[Abstract](93) [FullText HTML] (23) [PDF 2287KB](45) [Cited by] ()
With the continuous progress of science and technology, military targets are developing towards miniaturization, ultra-high speed and low detectivity, so the detection and identification ability of targets is also put forward higher requirements. Based on the deep analysis of point target imaging process and on the basis of energy distribution, based on abnormal Rayleigh distribution of point target energy calculation method, the infrared radiation characteristics and has a better precision than the experimental verification, it is concluded that the measurement deviation of radiation intensity can be controlled under 8%, and measuring the degree of discrete numerical smaller, can effectively distinguish between the point target and background. It is proved that the calculation method has good engineering applicability, high measurement accuracy and wide application prospect.
2023, 52(1): 20220278. doi: 10.3788/IRLA20220278
[Abstract](137) [FullText HTML] (34) [PDF 2448KB](56) [Cited by] ()
Vector measurement is an important technology for beam testing of antennas and quasi-optical systems in terahertz band. This paper introduces a terahertz vector measurement system based on a high-sensitivity AlGaN/GaN high-electron-mobility transistor (HEMT) terahertz detector integrated with a quasi-optical lens and waveguide together, which reached the noise equivalent power of −113 dBm/Hz in heterodyne mode at 340 GHz. A hardware circuit is established based on the double frequency-down-conversion technique to suppress phase noise in the system. The experimental results indicate that the minimum measurable power is 119 nW and the phase stability is better than 4° of the system. Measurement of the distribution of both terahertz amplitude and phase has been achieved based on this coherent AlGaN/GaN HEMT detector. An arrayed terahertz vector measurement system could be developed based on this work.
Diffuse reflection characteristics measurement of new type spaceborne solar calibration diffuser in ultraviolet band
2023, 52(1): 20220339. doi: 10.3788/IRLA20220339
[Abstract](92) [FullText HTML] (19) [PDF 2507KB](46) [Cited by] ()
The Lambertian diffuse reflectance characteristics of the spaceborne solar calibration diffuser and its radiation attenuation characteristics directly determine the long-term accuracy and stability of the on-orbit radiation calibration of space remote sensing instruments. In order to effectively improve the on-orbit radiation calibration accuracy of spaceborne ultraviolet hyperspectral detection instruments, based on the introduction of commonly used solar calibration diffuse reflector materials in the field of space remote sensing, a new type of ultraviolet wavelength diffuser material is proposed: high purity opaque fused silica material HOD, and the diffuse reflection Lambertian characteristics and radiation attenuation characteristics of the new high purity opaque Fused silica HOD diffuser and the traditional aluminum diffuser are compared by testing. The results show that after 32 equivalent solar hours (32ESH) of vacuum ultraviolet irradiation, the attenuation of the high purity opaque Fused silica HOD diffuser at the wavelength of 290 nm is 7.5%, which is better than 10% of the traditional aluminum diffuser. And the Lambertian maximum cosine deviation of the traditional aluminum diffuser around 290 nm is about 40%, while the high purity opaque Fused silica HOD diffuser is about 10%. Therefore, the diffuse reflection characteristics of the new high purity opaque Fused silica HOD diffuse reflector in the ultraviolet band are better than those of the traditional aluminum diffuser. The high purity opaque Fused silica hod diffuser has better diffuse reflection Lambertian characteristics and stronger vacuum ultraviolet radiation attenuation characteristics, so it can improve the long-term accuracy of the on-orbit radiometric calibration of space ultraviolet remote sensing instruments.
2023, 52(1): 20220414. doi: 10.3788/IRLA20220414
[Abstract](92) [FullText HTML] (24) [PDF 1708KB](51) [Cited by] ()
Redundant Rotating Inertial Navigation System (RRINS) can further improve the reliability of the system on the basis of traditional rotating inertial navigation system. Aiming at the high-precision initial alignment requirements of this type of system, A two-position initial alignment method was studied by taking the regular tetrahedral redundant rotating inertial navigation system as an example. Firstly, every three gyroscopes and three accelerometers constituted a combination. The zero bias correlation and redundancy configuration of the inertial device under each combination were established. And the RRINS two-position stop scheme was designed to estimate the zero bias of the corresponding inertial device. But in some special cases, the observation position needs to be increased. Then, the results obtained by each inertial device under different combinations were averaged, and the average value was used to compensate the measurement information of the corresponding inertial device. Finally, based on the compensated inertial device output performs the initial alignment of the RRINS. Mathematical simulation and experimental verification results show that the method can effectively estimate the zero bias of the inertial device under different two-position schemes. In the simulation, the bias estimation error of the gyroscope is within 4%, and the bias estimation error of the accelerometer is basically within 2%. Compared with the case without bias compensation, the initial alignment accuracy is improved by more than 10 times. In the experiment, the initial alignment accuracy in both horizontal and azimuth directions was improved, and the heading angle alignment error was reduced by about 100 times. At the same time, the method can also be extended to redundant rotating inertial navigation systems with other configuration schemes, which has certain reference significance for improving the initial alignment accuracy of such inertial navigation systems.
2022, 51(9): 20210952. doi: 10.3788/IRLA20210952
[Abstract](102) [FullText HTML] (21) [PDF 1564KB](39) [Cited by] ()
In order to solve the problem of limited internal space and difficult measurement of some workpiece, a point cloud rotating splicing method based on surface structured light was proposed. The reconstruction method of single field of surface structured light was introduced in this paper. The absolute phase value was obtained by combining four-step phase shift and complementary Gray code, and the camera and projector were calibrated by polynomial fitting method. The point cloud registration was studied based on the rotation plane of the wrist joint at the end of the manipulator. A calibration method based on the auxiliary camera was proposed, and the transformation relationship between the camera imaging coordinate system and the rotation plane coordinate system was given. The experimental results show that the method is suitable for measuring the inner wall of workpiece, and the average error of splicing is less than 0.05 mm, which meets the requirements of practical application.
2022, 51(9): 20210825. doi: 10.3788/IRLA20210825
[Abstract](131) [FullText HTML] (26) [PDF 1764KB](63) [Cited by] ()
The single photon scattering echo characteristics of targets were studied in this paper. An optical scattering characteristic measurement system was built based on infrared single photon detector and picosecond laser. The number of echo photons was used to characterize the optical scattering characteristics under the condition of single photon detection. In this experiment, the single photon scattering characteristics of targets with different shapes (sphere, cube, cylinder and cone) were studied. And the results were fitted by using the bidirectional reflection distribution function model. The experimental results were in good agreement with the theoretical fitting ones. Further, the single photon scattering characteristics of targets with different materials (ceramic tile, wood and wall brick) were studied, which were compared with the traditional wave scattering characteristics. This study provides a reference for the long-range target recognition and detection of single photon lidar.